Positive electrode additive for a lithium secondary battery, a method of manufacturing same, and a positive electrode for a lithium secondary battery including same

Abstract

A positive electrode additive for a lithium secondary battery can improve atmospheric stability. A method of manufacturing the same and a positive electrode for a lithium secondary battery includes the same. The positive electrode additive for a lithium secondary battery is used to manufacture the positive electrode for a lithium secondary battery and includes a lithium (Li)-based additive core and a coating layer of NbO X C y (0≤x≤2.5 and 0≤y≤1; where Nb=niobium, O=oxygen, C=carbon) formed on a surface of the additive core.

What is claimed is: 
     
         1 . A positive electrode additive, which is used to prepare a positive electrode for a lithium secondary battery, the positive electrode additive comprising:
 a lithium (Li)-based additive core; and   a coating layer of NbO X C y  (0≤x≤2.5 and 0≤y≤1; where Nb=niobium, O=oxygen, C=carbon) formed on a surface of the additive core.   
     
     
         2 . The positive electrode additive of  claim 1 , wherein the additive core is formed of Li 2 MO 2  (M=Ni, Cu; where Ni=nickel, Cu=copper). 
     
     
         3 . The positive electrode additive of  claim 1 , wherein the coating layer ranges from 1 to 10 wt % based on 100 wt % of the additive core. 
     
     
         4 . A method of manufacturing a positive electrode additive for a lithium secondary battery, which is used to manufacture a positive electrode for a lithium secondary battery, the method comprising:
 a core preparation operation of preparing a lithium (Li)-based additive core;   a coating solution preparation operation of preparing a coating solution to form a coating layer composed of NbO X C y  (0≤x≤2.5 and 0≤y≤1; where Nb=niobium, O=oxygen, C=carbon); and   a coating operation of coating a surface of the additive core with the coating solution and forming a coating layer.   
     
     
         5 . The method of  claim 4 , wherein, in the core preparation operation, lithium dioxide (Li 2 O) is reacted with a MO precursor (M=Ni, Cu) to prepare a powdered additive core of Li 2 MO 2  (M=Ni, Cu; where Ni=nickel, Cu=copper). 
     
     
         6 . The method of  claim 5 , wherein the core preparation operation includes:
 a core pelletization process of mixing and pelletizing Li 2 O and the MO precursors (M=Ni, Cu); and   a core sintering process of heating and sintering the pelletized core material in an inert atmosphere to obtain the additive core.   
     
     
         7 . The method of  claim 4 , wherein, in the coating solution preparation operation, the coating solution is prepared by dispersing niobium ethoxide (Nb(OC 2 H 5 ) 5 ) and urea (CH 4 N 2 O) at the same molar ratio in a solvent. 
     
     
         8 . The method of  claim 7 , wherein the coating operation includes:
 a dispersion operation of dispersing the additive core in the prepared coating solution;   a reaction operation of generating a reactant forming the coating layer on the surface of the additive core by stirring and reacting the additive core dispersed in the solvent with Nb(OC 2 H 5 ) 5  and CH 4 N 2 O;   a drying operation of drying the solvent in which the reactant is generated in an inert atmosphere; and   a sintering operation of sintering the dried reactant and producing an additive in the form of a powder.   
     
     
         9 . The method of  claim 8 , wherein, in the reaction operation, the additive core dispersed in the solvent, Nb(OC 2 H 5 ) 5 , and CH 4 N 2 O are stirred ranging from 300 to 400 revolutions-per-minute (rpm) for ap period of time ranging from 1 to 2 hours at room temperature, and the solvent is evaporated while reacting with Nb(OC 2 H 5 ) 5  and CH 4 N 2 O on the surface of the additive core. 
     
     
         10 . The method of  claim 8 , wherein, in the drying operation, the additive core having the reactant formed on the surface thereof is dried at a temperature ranging from 110 to 130° C. for a period of time ranging from 11 to 13 hours in a vacuum oven. 
     
     
         11 . The method of  claim 8 , wherein, in the sintering operation, the coating layer is formed on the surface of the additive core by performing heat treatment on the additive core having the reactant generated on the surface thereof at a temperature ranging from 250 to 350° C. for a period of time ranging from 3 to 5 hours in a sintering furnace in an argon (Ar) atmosphere. 
     
     
         12 . A positive electrode for a lithium secondary battery, the positive electrode including a positive electrode additive comprising:
 a lithium (Li)-based additive core; and   a coating layer of NbO X C y  (0≤x≤2.5 and 0≤y≤1; where Nb=niobium, O=oxygen, C=carbon) formed on a surface of the additive core.   
     
     
         13 . The positive electrode of  claim 12 , further comprising:
 a conductive material and a binder.   
     
     
         14 . A lithium secondary battery comprising the positive electrode according to  claim 12 . 
     
     
         15 . The lithium secondary battery of  claim 14 , further comprising:
 a negative electrode including a negative electrode active material; and   an electrolyte.